Comparing two rational numbers
Use fraction form:
Make the denominators the same and compare the numerators. The number with the smaller numerator is smaller. For example, to compare a/b and c/d, we rewrite
a/b=a*d/b*d
= ad/bd and c/d = c*b/d*b=bc/bd
Now just compare the numerators : "ad" and "bc"
Multiplying and Dividing Rational Numbers
Multiplying and dividing rational numbers in decimal form is the same as multiplying and dividing integers. The decimal place of the product is the same of all decimals of all multiplied numbers. For example, 3.12*2.4.
Solution => 3.12*2.4=7.488
When multiplying or dividing rational numbers in fractional form, you multiply the numerators (N*N) and then multiply the denominators (D*D).
When dividing rational numbers in fractional form, first take the reciprocal of the divisor, and then multiply the numerators and the denominators.
Example => 5/9 divided by 2/7 .
Solution => 5/9 * 7/2 = 35/18
Adding Rational numbers
Adding and Subtracting rational numbers in decimal form is the same as adding and subtracting integers.
Example => -3.54+2.79=-0.75
When adding or subtracting rational numbers in fractional form, first make the denominator equal, and then add or subtract the numerators.
Statement by Elaine
When you add two rational numbers, the sign depends on how many negative numbers you have.
------Incorrect Statement
When you add two rational numbers , sign of the result depend on sign of Bigger Rational number , that is whether sign behind larger rational number is either positive or Negative.
Now, if both the rational number which needs to be added
1.→ Are of positive sign , the expression yields Positive result.
6 +5=11
2.→If one is positive and another one is negative , one rational number must be subtracted from another and sign behind result is of larger rational number.
→10 +(-11)= -1, as 11 is greater and it has negative sign behind it, so result will be negative Integer.
→ -5+8=3,larger rational number is Positive.
3.→ If both are of negative sign , result will be negative rational number.
-5-6= -11
